Basically the details about the passwords of different users in a linux system are stored in two files namely passwd and shadow. These files are generally located under /etc .Here we make use of these files for recovering the password using the password cracking tool John -The Ripper and is included in Backtrack Linux.
Just follow the steps for recovering the password without resetting the same…
1. Download the ISO image of Backtrack Linux from here
2. Run the ISO image by making it bootable to USB using UNetbootin or writing to CD.
3. Mount the required linux partition to /mnt.(for GUI mode use the command startx)
4. Use the default root prompt to execute the following commands
4.a) unshadow “path to passwd file” “path to shadow file” > newfile
Eg: unshadow /mnt/etc/passwd /mnt/etc/shadow > newfile
4.b) john newfile
5. Passwords for different users will be displayed in a shortwhile.